1. Field of the Invention
The present invention relates to a process for producing a halogenated benzene derivative by halogenating benzene and/or a benzene derivative in a liquid phase. More particularly, the present invention relates to a process for selectively producing a p-substituted halobenzene derivative by halogenating benzene and/or a benzene derivative in a liquid phase using, as a catalyst, an alkali-treated L type zeolite.
2. Description of the Prior Art
Halogenated benzene derivatives are important raw materials or intermediates in various fields such as medicines, agricultural chemicals and organic synthesis chemistry. They are ordinarily produced by halogenating benzene and/or a benzene derivative in a liquid phase using, as a catalyst, a Lewis acid such as ferric chloride, antimony chloride or the like. For instance, dichlorobenzene (hereinafter abbreviated to DCB) is produced by blowing chlorine gas into benzene or monochlorobenzene (hereinafter abbreviated to MCB) in the presence of ferric chloride.
As is well known, in the production of a disubstituted benzene derivative by liquid phase halogenation of a mono-substituted benzene derivative, three isomers, namely, a 1,2-di-substituted benzene derivative (an o-isomer), a 1,3-di-substituted benzene derivative (an m-isomer) and a 1,4-di-substituted benzene derivative (a p-isomer) are formed as products, and the proportions of these isomers vary depending upon the kind of substituent possessed by the mono-substituted benzene derivative, the kind of catalyst used, etc. For instance, in the production of DCB by liquid phase chlorination of MCB in the presence of ferric chloride, the following three isomers are formed in the following proportions.
o-Dichlorobenzene: 30 to 40% PA0 m-Dichlorobenzene: 0 to 5% PA0 p-Dichlorobenzene: 60 to 70%
In the three kinds of isomers of di-substituted halobenzene derivatives, p-substituted halobenzene derivatives are most important industrially and are in greatest demand. Hence, a number of processes have hitherto been proposed for the selective production of p-substituted halobenzene derivatives.
These prior arts include processes for selectively producing a p-substituted halobenzene derivative by halogenating benzene and/or a benzene derivative using a zeolite as a catalyst. For instance, "Journal of Catalysis" 60, 110 (1979) describes the use of zeolite as a catalyst for bromination of halogenated benzene. In this literature, it is indicated that a p-substituted bromobenzene derivative can be produced selectively by using, as a bromination catalyst, various ion exchange zeolites, namely, X type and Y type zeolites. Further, "Tetrahedron Letters" 21, 3809 (1980) describes the chlorination of benzene using various catalysts such as ZSM-5, ZSM-11, mordenite, L type zeolite and Y type zeolite. It is indicated in the literature that L type zeolite, in particular, can produce p-dichlorobenzene at a high selectivity. Furthermore, for example, Japanese patent public disclosure (Laid-Open Publication ) Nos. 130227/1984, 144722/1984 and 163329/1984 disclose processes for halogenating benzene or an alkylbenzene using L type zeolite or Y type zeolite as a catalyst.
It is obvious from the prior arts that in halogenation of benzene and/or a benzene derivative, processes using a zeolite catalyst can produce a p-substituted halobenzene derivative at a higher selectivity than conventional processes using a Lewis acid catalyst (e.g., ferric chloride). However, the selectivity of a p-substituted halobenzene derivative in said prior art processes using a zeolite catalyst is still insufficient from an industrial viewpoint. Accordingly, it is desired to develop a process for producing a p-substituted halobenzene derivative at an enhanced selectivity.
On the other hand, with respect to the alkali treatment of L type zeolite, Japanese patent public disclosure (Laid-Open Publication ) No. 80333/1984, discloses a process for reforming a hydrocarbon using, as a catalyst, a noble metal (e.g., platinum) supported by an alkali-treated L type zeolite carrier. It is indicated in the literature that the use of said alkali treated L type zeolite as a catalyst carrier in the gas phase aromatization of aliphatic hydrocarbons can improve the life of the catalyst used.
However, it is impossible to predict from the above literature that the use of said alkali-treated L type zeolite catalyst for liquid phase halogenation of benzene and/or a benzene derivative can enhance the selectivity of a p-substituted halobenzene derivative.